1. Field of the Invention
The invention relates to an exhaust system member that constitutes a passage through which exhaust gas emitted from a combustion chamber of an internal combustion engine flows.
2. Description of Related Art
There is known an example of an exhaust system member of this type, which is formed of a pair of members each having a semicircular cross-sectional shape. These members are connected to each other by welding the facing portions of the members. FIG. 5 is a view that shows an example of such an exhaust system member 100. As shown in FIG. 5, a first facing portion 112 of a first member 111 bulges radially outward of the exhaust system member 100. A second facing portion 122 of a second member 121 is located at a radially inner side of the exhaust system member 100 with respect to the first facing portion 112. Overlapped portions of these first facing portion 112 and second facing portion 122 are welded overall along an axial direction of the exhaust system member 100. Thus, the first member 111 and the second member 121 are integrated with each other.
A cylindrical member is inserted into the exhaust system member 100 through an opening 101, and coupled portions of the cylindrical member and exhaust system member are welded to each other all around along an end portion of the exhaust system member 100. In the example of FIG. 5, relatively large gaps 102 are formed at the opening 101 of the exhaust system member 100 between the first member 111 and the second member 121. Therefore, at the time of welding the cylindrical member to the exhaust system member, a spatter that is produced through the welding may enter the inside of the exhaust system member 100 via the gaps 102.
There is suggested a member described in Japanese Patent Application Publication No. 2008-121550 (JP 2008-121550 A) as an exhaust system member that is able to inhibit entry of such a spatter. That is, as shown in FIG. 6, in the first facing portions 212 of the first member 211, portions other than both ends adjacent to the opening of the exhaust system member 200 serve as bulged portions 213 that bulge radially outward. On the other hand, the second facing portions 222 of the second member 221 have protruding portions 223 at locations corresponding to the bulged portions 213.
As shown in FIG. 7, the protruding portions 223 are located radially inward of the bulged portions 213 when the second member 221 is assembled to the first member 211 and then the first facing portions 212 and the second facing portions 222 are welded to each other. Thus, near the opening 201 of the exhaust system member 200, the end faces of the second facing portions 222 match the end faces of the first facing portions 212. Therefore, it is possible to narrow the gaps as shown in FIG. 5, formed at the opening 201 of the exhaust system member 200. As a result, a spatter, which is produced at the time when the cylindrical member 250 is inserted into the exhaust system member 200 through the opening 201 and then the coupled portions are welded to each other, is hard to enter the inside of the exhaust system member 200 by the narrowed amounts of the gaps.
However, in terms of manufacturing tolerances, assembling tolerances, and the like, of the first member 211 and the second member 221, it is difficult to completely eliminate the above-described gaps. Therefore, at the time of welding the first facing portions 212 and the second facing portions 222 overall along the axial direction, a spatter may enter the inside through the gaps.